Hi all,From today morning My arduino board Tx pin always is lit up... It shows a voltage of ~3.6V. I havent used a serial.print commands. Even Blinky codes cause Tx pins to go high... Is it the problem with the ATMEGA328 IC? because it was working fine till yesterday... Any way to rectify this?? Wat all could be the possible reasons why this Tx pin is showing continuous HIGH?Hoping for a fast reply

the problem is back even with new IC. any help on this?? Cant I declare Digital pin 0 to output? still watever code i run its now showing a voltage of 5V. What could be the problem??

A couple on points. First the board's TX led is driven by the on board USB serial converter chip (either FTDI or 8u2 depending on what specific arduino board you have), so if it's continously lit that could indicate something other then the 328 chip. Next the USB serial convertor chip while idle normally puts out a +5vdc high to the arduino pin 0 via a series wired 1k ohm isolation resistor. If you are not using serial commands you are free to set pin 0 mode to output and set it to LOW as that will have no problem overridding the HIGH from the serial convertor chip.

So can you upload sketches to your board, like blink? What are you wishing to do with pin 0 on the arduino?

Again what problem(s) are you trying to solve? And you really should post the code you are trying to run to show us what problem you are having.

So can you upload sketches to your board, like blink? What are you wishing to do with pin 0 on the arduino?

Yes. I can. But the problem is even the blinky code on any pin say pin 10 works... but still the Tx pin remains at high state...

I am trying to use pin 0 as a normal output pin. and I am not using serial commands... If u ask me will the pin 0 work? it works. because if i explicitly make it LOW if a particular condition is met Pin 0 output becomes zero. But the problem is when its in standy or not doing any operation on pin 0 like in blinky code on pin 13, Tx pin it goes high for no apparent reason.

I even tried setting Output to LOW in the setup function thinking that default value of Pin 0 may be HIGH and I will set it to LOW once in setup so that it low whwn rest of the program runs. but still Tx pin goes HIGH.

So can you upload sketches to your board, like blink? What are you wishing to do with pin 0 on the arduino?

Yes. I can. But the problem is even the blinky code on any pin say pin 10 works... but still the Tx pin remains at high state...

I am trying to use pin 0 as a normal output pin. and I am not using serial commands... If u ask me will the pin 0 work? it works. because if i explicitly make it LOW if a particular condition is met Pin 0 output becomes zero. But the problem is when its in standy or not doing any operation on pin 0 like in blinky code on pin 13, Tx pin it goes high for no apparent reason.

I even tried setting Output to LOW in the setup function thinking that default value of Pin 0 may be HIGH and I will set it to LOW once in setup so that it low whwn rest of the program runs. but still Tx pin goes HIGH.

and Currently its showing a voltage of 3.6V.

Again, if pin 0 is in it's default input pin mode you will still measure +5vdc on it because it's wired to the Tx pin of the serial USB convertor chip. I think you are making out a problem that is not a problem. Why must you not want to see a positive voltage on pin 0 if you are not using it?

Again, if pin 0 is in it's default input pin mode you will still measure +5vdc on it because it's wired to the Tx pin of the serial USB convertor chip.

but I explicitly made it a Output Pin. So it must behave as a normal output pin right??

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Why must you not want to see a positive voltage on pin 0 if you are not using it?

Well I am connecting a led to that pin so i dont want it to be ON everytime. I need to make it HIGH and LOW according to certain conditions.. and I usually want it to be LOW. So wont specifying a the pin to LOW in setup function solve the problem? Apparently it is not...